/* varobj support for Ada. Copyright (C) 2012-2013 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "defs.h" #include "ada-varobj.h" #include "ada-lang.h" #include "language.h" #include "valprint.h" /* Implementation principle used in this unit: For our purposes, the meat of the varobj object is made of two elements: The varobj's (struct) value, and the varobj's (struct) type. In most situations, the varobj has a non-NULL value, and the type becomes redundant, as it can be directly derived from the value. In the initial implementation of this unit, most routines would only take a value, and return a value. But there are many situations where it is possible for a varobj to have a NULL value. For instance, if the varobj becomes out of scope. Or better yet, when the varobj is the child of another NULL pointer varobj. In that situation, we must rely on the type instead of the value to create the child varobj. That's why most functions below work with a (value, type) pair. The value may or may not be NULL. But the type is always expected to be set. When the value is NULL, then we work with the type alone, and keep the value NULL. But when the value is not NULL, then we work using the value, because it provides more information. But we still always set the type as well, even if that type could easily be derived from the value. The reason behind this is that it allows the code to use the type without having to worry about it being set or not. It makes the code clearer. */ /* A convenience function that decodes the VALUE_PTR/TYPE_PTR couple: If there is a value (*VALUE_PTR not NULL), then perform the decoding using it, and compute the associated type from the resulting value. Otherwise, compute a static approximation of *TYPE_PTR, leaving *VALUE_PTR unchanged. The results are written in place. */ static void ada_varobj_decode_var (struct value **value_ptr, struct type **type_ptr) { if (*value_ptr) { *value_ptr = ada_get_decoded_value (*value_ptr); *type_ptr = ada_check_typedef (value_type (*value_ptr)); } else *type_ptr = ada_get_decoded_type (*type_ptr); } /* Return a string containing an image of the given scalar value. VAL is the numeric value, while TYPE is the value's type. This is useful for plain integers, of course, but even more so for enumerated types. The result should be deallocated by xfree after use. */ static char * ada_varobj_scalar_image (struct type *type, LONGEST val) { struct ui_file *buf = mem_fileopen (); struct cleanup *cleanups = make_cleanup_ui_file_delete (buf); char *result; ada_print_scalar (type, val, buf); result = ui_file_xstrdup (buf, NULL); do_cleanups (cleanups); return result; } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair designates a struct or union, compute the (CHILD_VALUE, CHILD_TYPE) couple corresponding to the field number FIELDNO. */ static void ada_varobj_struct_elt (struct value *parent_value, struct type *parent_type, int fieldno, struct value **child_value, struct type **child_type) { struct value *value = NULL; struct type *type = NULL; if (parent_value) { value = value_field (parent_value, fieldno); type = value_type (value); } else type = TYPE_FIELD_TYPE (parent_type, fieldno); if (child_value) *child_value = value; if (child_type) *child_type = type; } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair is a pointer or reference, return a (CHILD_VALUE, CHILD_TYPE) couple corresponding to the dereferenced value. */ static void ada_varobj_ind (struct value *parent_value, struct type *parent_type, struct value **child_value, struct type **child_type) { struct value *value = NULL; struct type *type = NULL; if (ada_is_array_descriptor_type (parent_type)) { /* This can only happen when PARENT_VALUE is NULL. Otherwise, ada_get_decoded_value would have transformed our parent_type into a simple array pointer type. */ gdb_assert (parent_value == NULL); gdb_assert (TYPE_CODE (parent_type) == TYPE_CODE_TYPEDEF); /* Decode parent_type by the equivalent pointer to (decoded) array. */ while (TYPE_CODE (parent_type) == TYPE_CODE_TYPEDEF) parent_type = TYPE_TARGET_TYPE (parent_type); parent_type = ada_coerce_to_simple_array_type (parent_type); parent_type = lookup_pointer_type (parent_type); } /* If parent_value is a null pointer, then only perform static dereferencing. We cannot dereference null pointers. */ if (parent_value && value_as_address (parent_value) == 0) parent_value = NULL; if (parent_value) { value = ada_value_ind (parent_value); type = value_type (value); } else type = TYPE_TARGET_TYPE (parent_type); if (child_value) *child_value = value; if (child_type) *child_type = type; } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair is a simple array (TYPE_CODE_ARRAY), return the (CHILD_VALUE, CHILD_TYPE) pair corresponding to the element at ELT_INDEX. */ static void ada_varobj_simple_array_elt (struct value *parent_value, struct type *parent_type, int elt_index, struct value **child_value, struct type **child_type) { struct value *value = NULL; struct type *type = NULL; if (parent_value) { struct value *index_value = value_from_longest (TYPE_INDEX_TYPE (parent_type), elt_index); value = ada_value_subscript (parent_value, 1, &index_value); type = value_type (value); } else type = TYPE_TARGET_TYPE (parent_type); if (child_value) *child_value = value; if (child_type) *child_type = type; } /* Given the decoded value and decoded type of a variable object, adjust the value and type to those necessary for getting children of the variable object. The replacement is performed in place. */ static void ada_varobj_adjust_for_child_access (struct value **value, struct type **type) { /* Pointers to struct/union types are special: Instead of having one child (the struct), their children are the components of the struct/union type. We handle this situation by dereferencing the (value, type) couple. */ if (TYPE_CODE (*type) == TYPE_CODE_PTR && (TYPE_CODE (TYPE_TARGET_TYPE (*type)) == TYPE_CODE_STRUCT || TYPE_CODE (TYPE_TARGET_TYPE (*type)) == TYPE_CODE_UNION) && !ada_is_array_descriptor_type (TYPE_TARGET_TYPE (*type)) && !ada_is_constrained_packed_array_type (TYPE_TARGET_TYPE (*type))) ada_varobj_ind (*value, *type, value, type); } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair is an array (any type of array, "simple" or not), return the number of children that this array contains. */ static int ada_varobj_get_array_number_of_children (struct value *parent_value, struct type *parent_type) { LONGEST lo, hi; if (!get_array_bounds (parent_type, &lo, &hi)) { /* Could not get the array bounds. Pretend this is an empty array. */ warning (_("unable to get bounds of array, assuming null array")); return 0; } /* Ada allows the upper bound to be less than the lower bound, in order to specify empty arrays... */ if (hi < lo) return 0; return hi - lo + 1; } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair is a struct or union, return the number of children this struct contains. */ static int ada_varobj_get_struct_number_of_children (struct value *parent_value, struct type *parent_type) { int n_children = 0; int i; gdb_assert (TYPE_CODE (parent_type) == TYPE_CODE_STRUCT || TYPE_CODE (parent_type) == TYPE_CODE_UNION); for (i = 0; i < TYPE_NFIELDS (parent_type); i++) { if (ada_is_ignored_field (parent_type, i)) continue; if (ada_is_wrapper_field (parent_type, i)) { struct value *elt_value; struct type *elt_type; ada_varobj_struct_elt (parent_value, parent_type, i, &elt_value, &elt_type); if (ada_is_tagged_type (elt_type, 0)) { /* We must not use ada_varobj_get_number_of_children to determine is element's number of children, because this function first calls ada_varobj_decode_var, which "fixes" the element. For tagged types, this includes reading the object's tag to determine its real type, which happens to be the parent_type, and leads to an infinite loop (because the element gets fixed back into the parent). */ n_children += ada_varobj_get_struct_number_of_children (elt_value, elt_type); } else n_children += ada_varobj_get_number_of_children (elt_value, elt_type); } else if (ada_is_variant_part (parent_type, i)) { /* In normal situations, the variant part of the record should have been "fixed". Or, in other words, it should have been replaced by the branch of the variant part that is relevant for our value. But there are still situations where this can happen, however (Eg. when our parent is a NULL pointer). We do not support showing this part of the record for now, so just pretend this field does not exist. */ } else n_children++; } return n_children; } /* Assuming that the (PARENT_VALUE, PARENT_TYPE) pair designates a pointer, return the number of children this pointer has. */ static int ada_varobj_get_ptr_number_of_children (struct value *parent_value, struct type *parent_type) { struct type *child_type = TYPE_TARGET_TYPE (parent_type); /* Pointer to functions and to void do not have a child, since you cannot print what they point to. */ if (TYPE_CODE (child_type) == TYPE_CODE_FUNC || TYPE_CODE (child_type) == TYPE_CODE_VOID) return 0; /* All other types have 1 child. */ return 1; } /* Return the number of children for the (PARENT_VALUE, PARENT_TYPE) pair. */ int ada_varobj_get_number_of_children (struct value *parent_value, struct type *parent_type) { ada_varobj_decode_var (&parent_value, &parent_type); ada_varobj_adjust_for_child_access (&parent_value, &parent_type); /* A typedef to an array descriptor in fact represents a pointer to an unconstrained array. These types always have one child (the unconstrained array). */ if (ada_is_array_descriptor_type (parent_type) && TYPE_CODE (parent_type) == TYPE_CODE_TYPEDEF) return 1; if (TYPE_CODE (parent_type) == TYPE_CODE_ARRAY) return ada_varobj_get_array_number_of_children (parent_value, parent_type); if (TYPE_CODE (parent_type) == TYPE_CODE_STRUCT || TYPE_CODE (parent_type) == TYPE_CODE_UNION) return ada_varobj_get_struct_number_of_children (parent_value, parent_type); if (TYPE_CODE (parent_type) == TYPE_CODE_PTR) return ada_varobj_get_ptr_number_of_children (parent_value, parent_type); /* All other types have no child. */ return 0; } /* Describe the child of the (PARENT_VALUE, PARENT_TYPE) pair whose index is CHILD_INDEX: - If CHILD_NAME is not NULL, then a copy of the child's name is saved in *CHILD_NAME. This copy must be deallocated with xfree after use. - If CHILD_VALUE is not NULL, then save the child's value in *CHILD_VALUE. Same thing for the child's type with CHILD_TYPE if not NULL. - If CHILD_PATH_EXPR is not NULL, then compute the child's path expression. The resulting string must be deallocated after use with xfree. Computing the child's path expression requires the PARENT_PATH_EXPR to be non-NULL. Otherwise, PARENT_PATH_EXPR may be null if CHILD_PATH_EXPR is NULL. PARENT_NAME is the name of the parent, and should never be NULL. */ static void ada_varobj_describe_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index, char **child_name, struct value **child_value, struct type **child_type, char **child_path_expr); /* Same as ada_varobj_describe_child, but limited to struct/union objects. */ static void ada_varobj_describe_struct_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index, char **child_name, struct value **child_value, struct type **child_type, char **child_path_expr) { int fieldno; int childno = 0; gdb_assert (TYPE_CODE (parent_type) == TYPE_CODE_STRUCT); for (fieldno = 0; fieldno < TYPE_NFIELDS (parent_type); fieldno++) { if (ada_is_ignored_field (parent_type, fieldno)) continue; if (ada_is_wrapper_field (parent_type, fieldno)) { struct value *elt_value; struct type *elt_type; int elt_n_children; ada_varobj_struct_elt (parent_value, parent_type, fieldno, &elt_value, &elt_type); if (ada_is_tagged_type (elt_type, 0)) { /* Same as in ada_varobj_get_struct_number_of_children: For tagged types, we must be careful to not call ada_varobj_get_number_of_children, to prevent our element from being fixed back into the parent. */ elt_n_children = ada_varobj_get_struct_number_of_children (elt_value, elt_type); } else elt_n_children = ada_varobj_get_number_of_children (elt_value, elt_type); /* Is the child we're looking for one of the children of this wrapper field? */ if (child_index - childno < elt_n_children) { if (ada_is_tagged_type (elt_type, 0)) { /* Same as in ada_varobj_get_struct_number_of_children: For tagged types, we must be careful to not call ada_varobj_describe_child, to prevent our element from being fixed back into the parent. */ ada_varobj_describe_struct_child (elt_value, elt_type, parent_name, parent_path_expr, child_index - childno, child_name, child_value, child_type, child_path_expr); } else ada_varobj_describe_child (elt_value, elt_type, parent_name, parent_path_expr, child_index - childno, child_name, child_value, child_type, child_path_expr); return; } /* The child we're looking for is beyond this wrapper field, so skip all its children. */ childno += elt_n_children; continue; } else if (ada_is_variant_part (parent_type, fieldno)) { /* In normal situations, the variant part of the record should have been "fixed". Or, in other words, it should have been replaced by the branch of the variant part that is relevant for our value. But there are still situations where this can happen, however (Eg. when our parent is a NULL pointer). We do not support showing this part of the record for now, so just pretend this field does not exist. */ continue; } if (childno == child_index) { if (child_name) { /* The name of the child is none other than the field's name, except that we need to strip suffixes from it. For instance, fields with alignment constraints will have an __XVA suffix added to them. */ const char *field_name = TYPE_FIELD_NAME (parent_type, fieldno); int child_name_len = ada_name_prefix_len (field_name); *child_name = xstrprintf ("%.*s", child_name_len, field_name); } if (child_value && parent_value) ada_varobj_struct_elt (parent_value, parent_type, fieldno, child_value, NULL); if (child_type) ada_varobj_struct_elt (parent_value, parent_type, fieldno, NULL, child_type); if (child_path_expr) { /* The name of the child is none other than the field's name, except that we need to strip suffixes from it. For instance, fields with alignment constraints will have an __XVA suffix added to them. */ const char *field_name = TYPE_FIELD_NAME (parent_type, fieldno); int child_name_len = ada_name_prefix_len (field_name); *child_path_expr = xstrprintf ("(%s).%.*s", parent_path_expr, child_name_len, field_name); } return; } childno++; } /* Something went wrong. Either we miscounted the number of children, or CHILD_INDEX was too high. But we should never reach here. We don't have enough information to recover nicely, so just raise an assertion failure. */ gdb_assert_not_reached ("unexpected code path"); } /* Same as ada_varobj_describe_child, but limited to pointer objects. Note that CHILD_INDEX is unused in this situation, but still provided for consistency of interface with other routines describing an object's child. */ static void ada_varobj_describe_ptr_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index, char **child_name, struct value **child_value, struct type **child_type, char **child_path_expr) { if (child_name) *child_name = xstrprintf ("%s.all", parent_name); if (child_value && parent_value) ada_varobj_ind (parent_value, parent_type, child_value, NULL); if (child_type) ada_varobj_ind (parent_value, parent_type, NULL, child_type); if (child_path_expr) *child_path_expr = xstrprintf ("(%s).all", parent_path_expr); } /* Same as ada_varobj_describe_child, limited to simple array objects (TYPE_CODE_ARRAY only). Assumes that the (PARENT_VALUE, PARENT_TYPE) pair is properly decoded. This is done by ada_varobj_describe_child before calling us. */ static void ada_varobj_describe_simple_array_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index, char **child_name, struct value **child_value, struct type **child_type, char **child_path_expr) { struct type *index_desc_type; struct type *index_type; int real_index; gdb_assert (TYPE_CODE (parent_type) == TYPE_CODE_ARRAY); index_desc_type = ada_find_parallel_type (parent_type, "___XA"); ada_fixup_array_indexes_type (index_desc_type); if (index_desc_type) index_type = TYPE_FIELD_TYPE (index_desc_type, 0); else index_type = TYPE_INDEX_TYPE (parent_type); real_index = child_index + ada_discrete_type_low_bound (index_type); if (child_name) *child_name = ada_varobj_scalar_image (index_type, real_index); if (child_value && parent_value) ada_varobj_simple_array_elt (parent_value, parent_type, real_index, child_value, NULL); if (child_type) ada_varobj_simple_array_elt (parent_value, parent_type, real_index, NULL, child_type); if (child_path_expr) { char *index_img = ada_varobj_scalar_image (index_type, real_index); struct cleanup *cleanups = make_cleanup (xfree, index_img); /* Enumeration litterals by themselves are potentially ambiguous. For instance, consider the following package spec: package Pck is type Color is (Red, Green, Blue, White); type Blood_Cells is (White, Red); end Pck; In this case, the litteral "red" for instance, or even the fully-qualified litteral "pck.red" cannot be resolved by itself. Type qualification is needed to determine which enumeration litterals should be used. The following variable will be used to contain the name of the array index type when such type qualification is needed. */ const char *index_type_name = NULL; /* If the index type is a range type, find the base type. */ while (TYPE_CODE (index_type) == TYPE_CODE_RANGE) index_type = TYPE_TARGET_TYPE (index_type); if (TYPE_CODE (index_type) == TYPE_CODE_ENUM || TYPE_CODE (index_type) == TYPE_CODE_BOOL) { index_type_name = ada_type_name (index_type); if (index_type_name) index_type_name = ada_decode (index_type_name); } if (index_type_name != NULL) *child_path_expr = xstrprintf ("(%s)(%.*s'(%s))", parent_path_expr, ada_name_prefix_len (index_type_name), index_type_name, index_img); else *child_path_expr = xstrprintf ("(%s)(%s)", parent_path_expr, index_img); do_cleanups (cleanups); } } /* See description at declaration above. */ static void ada_varobj_describe_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index, char **child_name, struct value **child_value, struct type **child_type, char **child_path_expr) { /* We cannot compute the child's path expression without the parent's path expression. This is a pre-condition for calling this function. */ if (child_path_expr) gdb_assert (parent_path_expr != NULL); ada_varobj_decode_var (&parent_value, &parent_type); ada_varobj_adjust_for_child_access (&parent_value, &parent_type); if (child_name) *child_name = NULL; if (child_value) *child_value = NULL; if (child_type) *child_type = NULL; if (child_path_expr) *child_path_expr = NULL; if (ada_is_array_descriptor_type (parent_type) && TYPE_CODE (parent_type) == TYPE_CODE_TYPEDEF) { ada_varobj_describe_ptr_child (parent_value, parent_type, parent_name, parent_path_expr, child_index, child_name, child_value, child_type, child_path_expr); return; } if (TYPE_CODE (parent_type) == TYPE_CODE_ARRAY) { ada_varobj_describe_simple_array_child (parent_value, parent_type, parent_name, parent_path_expr, child_index, child_name, child_value, child_type, child_path_expr); return; } if (TYPE_CODE (parent_type) == TYPE_CODE_STRUCT) { ada_varobj_describe_struct_child (parent_value, parent_type, parent_name, parent_path_expr, child_index, child_name, child_value, child_type, child_path_expr); return; } if (TYPE_CODE (parent_type) == TYPE_CODE_PTR) { ada_varobj_describe_ptr_child (parent_value, parent_type, parent_name, parent_path_expr, child_index, child_name, child_value, child_type, child_path_expr); return; } /* It should never happen. But rather than crash, report dummy names and return a NULL child_value. */ if (child_name) *child_name = xstrdup ("???"); } /* Return the name of the child number CHILD_INDEX of the (PARENT_VALUE, PARENT_TYPE) pair. PARENT_NAME is the name of the PARENT. The result should be deallocated after use with xfree. */ char * ada_varobj_get_name_of_child (struct value *parent_value, struct type *parent_type, const char *parent_name, int child_index) { char *child_name; ada_varobj_describe_child (parent_value, parent_type, parent_name, NULL, child_index, &child_name, NULL, NULL, NULL); return child_name; } /* Return the path expression of the child number CHILD_INDEX of the (PARENT_VALUE, PARENT_TYPE) pair. PARENT_NAME is the name of the parent, and PARENT_PATH_EXPR is the parent's path expression. Both must be non-NULL. The result must be deallocated after use with xfree. */ char * ada_varobj_get_path_expr_of_child (struct value *parent_value, struct type *parent_type, const char *parent_name, const char *parent_path_expr, int child_index) { char *child_path_expr; ada_varobj_describe_child (parent_value, parent_type, parent_name, parent_path_expr, child_index, NULL, NULL, NULL, &child_path_expr); return child_path_expr; } /* Return the value of child number CHILD_INDEX of the (PARENT_VALUE, PARENT_TYPE) pair. PARENT_NAME is the name of the parent. */ struct value * ada_varobj_get_value_of_child (struct value *parent_value, struct type *parent_type, const char *parent_name, int child_index) { struct value *child_value; ada_varobj_describe_child (parent_value, parent_type, parent_name, NULL, child_index, NULL, &child_value, NULL, NULL); return child_value; } /* Return the type of child number CHILD_INDEX of the (PARENT_VALUE, PARENT_TYPE) pair. */ struct type * ada_varobj_get_type_of_child (struct value *parent_value, struct type *parent_type, int child_index) { struct type *child_type; ada_varobj_describe_child (parent_value, parent_type, NULL, NULL, child_index, NULL, NULL, &child_type, NULL); return child_type; } /* Return a string that contains the image of the given VALUE, using the print options OPTS as the options for formatting the result. The resulting string must be deallocated after use with xfree. */ static char * ada_varobj_get_value_image (struct value *value, struct value_print_options *opts) { char *result; struct ui_file *buffer; struct cleanup *old_chain; buffer = mem_fileopen (); old_chain = make_cleanup_ui_file_delete (buffer); common_val_print (value, buffer, 0, opts, current_language); result = ui_file_xstrdup (buffer, NULL); do_cleanups (old_chain); return result; } /* Assuming that the (VALUE, TYPE) pair designates an array varobj, return a string that is suitable for use in the "value" field of the varobj output. Most of the time, this is the number of elements in the array inside square brackets, but there are situations where it's useful to add more info. OPTS are the print options used when formatting the result. The result should be deallocated after use using xfree. */ static char * ada_varobj_get_value_of_array_variable (struct value *value, struct type *type, struct value_print_options *opts) { char *result; const int numchild = ada_varobj_get_array_number_of_children (value, type); /* If we have a string, provide its contents in the "value" field. Otherwise, the only other way to inspect the contents of the string is by looking at the value of each element, as in any other array, which is not very convenient... */ if (value && ada_is_string_type (type) && (opts->format == 0 || opts->format == 's')) { char *str; struct cleanup *old_chain; str = ada_varobj_get_value_image (value, opts); old_chain = make_cleanup (xfree, str); result = xstrprintf ("[%d] %s", numchild, str); do_cleanups (old_chain); } else result = xstrprintf ("[%d]", numchild); return result; } /* Return a string representation of the (VALUE, TYPE) pair, using the given print options OPTS as our formatting options. */ char * ada_varobj_get_value_of_variable (struct value *value, struct type *type, struct value_print_options *opts) { char *result = NULL; ada_varobj_decode_var (&value, &type); switch (TYPE_CODE (type)) { case TYPE_CODE_STRUCT: case TYPE_CODE_UNION: result = xstrdup ("{...}"); break; case TYPE_CODE_ARRAY: result = ada_varobj_get_value_of_array_variable (value, type, opts); break; default: if (!value) result = xstrdup (""); else result = ada_varobj_get_value_image (value, opts); break; } return result; }